Electrical connection of coaxial cable ends

ABSTRACT

A connection for coaxial cable ends in which a connection is obtained between the respective cable dielectrics with the aid of connection pieces of electrically insulating material engaging slots in the dielectric.

Gommans et al.

[ Apr. 16, 1974 ELECTRICAL CONNECTION OF COAXIAL CABLE ENDS Inventors:Hubertus Johannes Josephus Gommans; Josephus Gerardus HenricusStikkelbroeck, both of Venlo, Netherlands U.S. Philips Corporation, New

Assignee:

York, N.Y.

Filed: Jan. 29, 1973 Appl. No.: 327,491

Foreign Application Priority Data [56] References Cited UNITED STATESPATENTS 3,151,211 9/1964 Reid et a1. 174/92 X 288,311 11/1883 Cobb174/92 2,657,252 10/1953 Mildner et al. 174/88 C 2,937,228 5/1960Robinson 174/88 C 3,001,003 9/1961 Robinson 174/88 C PrimaryExaminer-Darrell L. Clay Attorney, Agent, or Firm-Frank P. Trifari [57]ABSTRACT A connection for coaxial cable ends in which a con- Feb. 8,1972 Netherlands 01606 nection is obtained between the respective cabledielectrics with the aid of connection pieces of electri- U.S. Cl 174/88C, 174/92, 339/103 R, cally insulating material engaging slots in thedielec- 339/176 R tric. Int. Cl l-l02g 15/08 Field of Search 174/88 c,92, 93, 75 c, 4 Claims 8 W 174/89; 315. 117? R, 177R, 71 1 103 MPATENTEMPR 16 m4 3804-372 SHEET 1 OF E ELECTRICAL CONNECTION F COAXIALCABL ENDS The invention relates to an electrical connection of twocoaxial cable ends each consisting of a central conductor, a soliddielectric surrounding the central conductor, a cylindrical outerconductor and a sheath, the central conductors and the outer conductorsbeing electrically connected respectively together in a conventionalmanner, for example, by means of clamping connections. The inventionfurther relates to a method of manufacturing such a connection. As aresult of the increasing use of communal aerial systems particularlyalso for television reception there is a great need of reliableconnections between coaxial cable ends of equal or unequal diameterswith respect to each other.

The most important requirement imposed on such connections is thatreflections which deteriate the signal distributed through the cablemust not be produced. In addition the connection must be water resistantand it must be able to withstand pulling forces occuring during normalhandling of the cable.

The existing connections are in general of a complicated nature and areexpensive and easily give rise to errorsQThey can only be applied byspecially trained people.

In some known connections the electrical connection between the centralconductors is stressed where the cable is subjected to pulling forces.This may give rise to unwanted alterations in the electrical behaviourof the cable. In other connections the sheath is stressed under suchcircumstances and may be damaged so that moisture can penetrate thecable.

An object of the invention is to provide a connection which can beapplied without errors and with as few tools as possible by untrainedpersonnel after some instructions, which connections may be subjected topulling forces without unwanted alterations occurring in the electricalbehaviour of the cable.

According to the invention a connection between two coaxial cable endswhich satisfied this condition is characterized in that the cable endsare mechanically connected together by means of connection pieces ofelectrically insulating material provided with parts projecting in thedirection of the central conductor, said parts being accommodated inrecesses in the solid dielectrics of the respective cable ends.

A preferred embodiment of the connection according to the invention ischaracterized in that the connection pieces consist of shells ofelectrically insulating material which are provided on their inner sidewith at least two radially varying elevations engaging radially varyingslots in the cable dielectric of the two cable ends. From an electricalpoint of view it is necessary that the impedance at the area of theconnection is equal to that of the cables connected'together. Thus,before the shells are provided such a quantity of that part of thedielectric located between the radial slot and the cable end is radiallyremoved that after the shells are applied the outer diameter of theshells coincides with the original outer diameter of the dielectricwhich was located at the area of the connection. The thickness of thepart removed from the cable is then equal or substantially equal to thethickness of the shells. It is achieved thereby that the diameter of thecable dielectric between the radial slots and the cable end plus thethickness of the shell at that area is equal or substantially equal tothe original diameter of the cable dielectric in that area.

In order to realize a satisfactory electrical connection between thecentral conductors, the central conductors are exposed over a givendistance and these exposed ends are slid in a metal bush provided withan envelope of insulating material. The metal bush may be provided withone or more axial slots and may have a slightly smaller inner diameterthan the diameter of the central conductor so that a clamping connectionis obtained. The outer diameter of the insulating envelope of thiscylindrical connection piece is preferably equal to the diameter of theadjacent parts of the cable dielectric. If these diameters differ, thediameter at each end is equal to the diameter of the adjacent cabledielectric. The diameter between the two ends then varies, for ex.-ample, regularly with the distance so that a conical shape is obtainedwhile it is of course to be ensured that the impedance at that area isequal to that of the cable ends. This envelope may be connected to oneof the shells. An electrical connection between the cylindrical outerconductors may be obtained, for example, with the aid of shells of metaloverlapping parts of the outer conductor and being provided in aclamping manner on the outer conductors with the aid of a clampingdevice, for example, clamping rings. These shells are preferablyprovided with adjoining profiled edges at least in the area of theconnection so as to avoid outward radiation. Subsequently an outersheath may be provided, for example, by applying a heat shrinkableplastics tube or a self-vulcanizing sealing tape to the assembly.

A preferred embodiment of the invention and a method of manufacturingsuch a connection will not be described in greater detail with referenceto the accompanying drawing.

FIGS. 11 to 3 show axial cross-sections of cable ends at variouspreparatory stages for the provision of the connection according to theinvention,

FIG. 4 shows a connection according to the invention in an axialcross-section.

FIG. 5 shows the cylindrical connection piece in a radial cross-section.

FIG. 6 shows a shell-shaped connection piece axial cross-section.

FIG. 7 shows two shell-shaped connection pieces in a radial elevationview.

FIG. 8 shows a finished connection in an axial crosssection.

FIG. I shows one end of a coaxial cable in an axial cross-section. Thecable comprises a central conductor 1 of solid copper, a soliddielectric 2 of polyethylene, an outer conductor 3 of copper foil and/orcopper stranded wire and an outer sheath 4 of polyethylene. An equalpart of the sheath 4 and the outer conductor 3 is removed from the cableend, while the outer sheath 4 is radially cut at 5 as far as the outerconductor 3. Subsequently part of the dielectric 2 is removed so thatafter this operation the central conductor partly projects beyond thedielectric (FIG. 2). Two shells (6 and 7) are removed from thedielectric. If desired, this operation may be combined with the previousoperation, unbaring part of the central conductors. The slot obtained byremoving the shell 6 serves to accommodate the'part 9 projecting on theinner side of the shell 8. The reduction in diameter of the dielectricby removing the shell 7 serves to accommodate the thicl ness of theshell 8 so that, as shown in FIG. 4, the outer in an diameter at thearea of the connection coincides with that of the solid dielectric ofthe cable ends. Subsequently the sheath part 4A is removed. The parts ofthe central conductor 1 projecting outside the solid dielectric are slidinto the connection piece which is shown in a radial cross-section inFIG. 5. The connection piece 10 consists of a metal bush 11 which mayhave a slightly smaller diameter than the central conductors and may beprovided with one or more axially varying slots so as to obtain aclamping tit, and an envelope of insulating material 12. Since theprovision of the metal bush 11 causes the conductor diameter at the areaof this connection to increase relatively, it is generally necessary toadapt, or in this case to decrease the dielectric constant of thematerial for the sheath 12 if this is the same material as that used forthe solid dielectric 2. This may be realized, for example, by pro--viding a plurality of ducts 13 (see FIG. 5) in the envelope 12parallelto the axis.

Subsequently the shells 8 are provided while the projecting edges 9engage the recesses obtained by removing the shell 6. FIG. 6 is alongitudinal cross-section of such a shell 8. The shell 8 may bemanufactured from the same electrically insulating material as that forthe solid dielectric 2, for example, polyethylene. Two shells combinedmay constitute a closed cylinder sheath and it is alternatively possibleto form the shells in such a manner that three or more shells constitutea closed cylinder sheath. Generally it is, however, preferred to limitthe number of shells so that also the number of seams through whichmoisture might penetrate the cable is limited. FIG. 7 is a radialelevational view of two shells 8. In order to obtain a satisfactorysealing from moisture the tangent planes 14 may be provided with fittingridges and slots. As a further step to prevent moisture penetration athin coating of water repellent mass, for example, polyethylene wax orsilicon grease may be provided between all parts. Subsequently twocopper shells 15 and 16 are provided on the connection in an overlappingelectrical contact with the outer conductors 3 and secured with the aidof clamping rings 18. Subsequently a tube of elastic electricallyinsulating material 17, for example, a shrink tube of polyethylenepreviously provided on one of the cable ends is slid over the assembly.This tube 17 serves as the outer sheath. In order to obtain asatisfactory sealing from moisture penetration it is preferred to havepart of this tube 17 overlap the sheath 4 as it is shown in the Figure.

A connection as the one shown may be subjected to pulling forcesnormally occuring during handling of the cable without the risk ofvarying the electrical properties of the connection between the cableends or the impedance at that area. Such a connection withstands withoutany risk realing and derealing on reels. The provision of cable muffs isgenerally not necessary because a sufficient water-tightness is obtainedwith the construction according to the invention.

A connection according to the invention may be used, for example, forconnecting cable ends having a total diameter of 15 mms. or more.

What is claimed is:

1. Electrical connection of two coaxial cable ends each having a centralconductor, a solid dielectric surrounding the central conductor, acylindrical outer conductor and a sheath, the central conductors and theouter conductors being electrically connected together, connectionpieces of electrically insulating material mechanically connecting theends of said cables together, said connection pieces being provided withparts projecting in the direction of the central conductor, said partsengaging recesses in the solid dielectrics of the respective cable ends.

2. Electrical connection of two co-axial cable ends as claimed in claim1, wherein said connection pieces comprise shells of electricallyinsulating material being provided with at least two radially extendingelevations engaging radially extending slots in the dielectric of thetwo cable ends.

3. An electrical connection of two coaxial cable ends as claimed inclaim 2, wherein the diameter of the cable dielectric between theradially extending slots plus the thickness of the shells at that areais substantially equal to the original diameter of the cable dielectricat that area.

4. An electrical connection of two coaxial cable ends as claimed inclaim 3, wherein the central conductors project outside the cabledielectric of the cable ends, and further comprising a metal bush slidover the two ends of the central conductors electrically connecting saidconductors together and an envelope of electrically insulating materialenveloping said bush, the diameter of the envelope at each end beingsubstantially equal to that of the adjacent cable dielectric parts.

m I UNITED STATESIPATENVT OFFICE CERTIFICATE OF CORRECTION Patent No;38049723 Datedv April l6, 1974 Inventor-( HUBERTUS JOHANNES JOSEPHUSGOMMANS ET AL It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

In the heading:

under "[30] Foreign ApplicatiorrPriority Data" 01606 should be -720l606Signed "and sealed this 24th day of September 1974,

(SEAL) Attest: v

McCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner ofPatents @3 2 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPatent No; 3804972- v I Dated I April 1.6, 1974 Inventor(s) HUYBERTUSJOHANNES JOSEPHUS GOMMANS ET AL It is certified that error apfiears inthe above-identified patent and that said Let ters Patent; are hefebycorrected as shown below:

In the heading:

under ":[30] Foreign Applicatioh Priority Data" "01606" should be--720l606 Signed and sealed this 24th day of September 1974,

(SEAL) Attest:

C. MARSHALL DANN Commissioner of Patents MCCOY M. GIBSON JR. AttestingOfficer

1. Electrical connection of two coaxial cable ends each having a centralconductor, a solid dielectric surrounding the central conductor, acylindrical outer conductor and a sheath, the central conductors and theouter conductors being electrically connected together, connectionpieces of electrically insulating material mechanically connecting theends of said cables together, said connection pieces being provided withparts projecting in the direction of the central conductor, said partsengaging recesses in the solid dielectrics of the respective cable ends.2. Electrical connection of two co-axial cable ends as claimed in claim1, wherein said connection pieces comprise shells of electricallyinsulating material being provided with at least two radially extendingelevations engaging radially extending slots in the dielectric of thetwo cable ends.
 3. An electrical connection of two coaxial cable ends asclaimed in claim 2, wherein the diameter of the cable dielectric betweenthe radially extending slots plus The thickness of the shells at thatarea is substantially equal to the original diameter of the cabledielectric at that area.
 4. An electrical connection of two coaxialcable ends as claimed in claim 3, wherein the central conductors projectoutside the cable dielectric of the cable ends, and further comprising ametal bush slid over the two ends of the central conductors electricallyconnecting said conductors together and an envelope of electricallyinsulating material enveloping said bush, the diameter of the envelopeat each end being substantially equal to that of the adjacent cabledielectric parts.